That study led to Dr. Gerard K. O’Neill’s proposal for
Island One, a relatively small Bernal Sphere. This was followed by the larger
Island Two (which, it was hoped, would provide a more practical industrial
base). By the time O’Neill got to Island Three, he’d evolved to a different
shape, the O’Neill Cylinder (we’ll discuss that design in a future post). Other
research rooted in the Bernal Sphere eventually led to a toroidal design, often
called a Stanford Torus.

The wine-tasting party doesn't seem to mind if the world is inside-out.

What would it be like, to live in a Bernal Sphere? Artwork from the mid-1970s gives us a glimpse of an inside-out world, in which you
could see the other side of the colony “up in the sky.” I don’t know about you,
but I think that would give me terrible vertigo.

Ultimately, I decided the Bernal Sphere was not the design for my fictional space
station. If I didn’t want to imagine living there, why would I try to make my characters do so? Might recall O'Neill apparently moved away from the original sphere-focused idea, too, once he looked into it more. But although my fictional Rana Habitat Space Station didn't turn out to be a Bernal Sphere, the design gave me some interesting ideas. I hope you've enjoyed this exploration.